Hi everybody, in my country the 6n138/139 optocoupler is a little expensive and some times a hard to find component, and searching in the web I found an alternative circuit with the 4n26 or 4n36 (I tested it with both) - comes in PDIP-6 and this is the equivalent circuit for using instead of 6n138/139:
I’m not sure but if you look at the fairchild datasheet appears a lot of others optocouplers - maybe those works too.
I use a 4n25, since that’s the only optocoupler my local Maplin had. Never had any problems with it.
Is there meant to be a pic there?
Edit: I forgot I can see source of posts hehe the original link is:
http://img300.imageshack.us/img300/5084/circuitoconel4n26o4n36hm2.gif
I guess imagesHack is being lame with referrers…
Rasteri are you using the 4n25 as a drop-in replacement or what?
Rasteri are you using the 4n25 as a drop-in replacement or what?
Unfortunately not - the pinouts completely different (for a start there’s two less…) I’ve attached the circuit I’m using, I dunno if it’s an optimal solution but it certainly works.
EDIT : My schematic was wrong, LyleHaze’s is better (see below)
Your pin numbers have 4 and 6 swapped.
This might confuse somebody that tries to wire this up.
This one has them corrected.
Also, this circuit should have a pullup resistor for
pin 5 (to RX). It might work without it, but for the
price of a resistor, why take chances?
Have Fun,
LyleHaze
fixed it, now are correct - I tried before a simple circuit like yours, but it doesn’t works, I’ll try your circuit. Thanks.
*ahem* cross post.
very useful, though. ;D
